Project Summary Diagnostic monitoring of bone fracture healing is critical for the detection of delayed union or non-union. However, the course of fracture healing is not easily diagnosed during the early healing phase (first 4 weeks post-operative), when the value of standard radiographic information is limited due to the paucity of mineralized tissue within the fracture site and when the administration of additional therapies (such as osteobiologics) could be implemented with greater efficacy. In order to address this critical need, we have developed a radio- frequency system in which an external antenna electromagnetically couples with an implanted biocompatible, microelectromechanical system (bioMEMS) sensor to measure loading at the fracture site, and we have conclusively shown using a large animal model that these data can be used to predict the fracture's healing cascade during the early healing phase. We have advanced this work to develop a non-invasive measurement system in which the external antenna couples directly with the implanted hardware (such as a fracture fixation plate) to measure deformations due to an applied load (?direct electromagnetic coupling?, DEC), eliminating the need for an implanted sensor. The DEC technique has been evaluated through computational simulations, ex vivo experiments, and exploratory patient tests, which have demonstrated the efficacy for monitoring changes in fracture stability over the course of healing in a clinical setting. Our large animal study demonstrated that these fracture stability measurement systems are most effective at predicting fracture healing outcomes by utilizing frequent (bi-weekly) data collection to track changes in the temporal loading profile. However, clinical data collection opportunities are limited by the standard patient follow-up schedule (typically once every four weeks). Therefore, we propose to build upon our existing patient testing system to develop a novel digital health DEC (dhDEC) device in which the patient can perform data collection at their home and transmit these data for analyses in order to predict fracture healing outcomes. The device will consist of a loading frame for applying bending magnitudes up to 8 Nm to the patient's fractured limb, electromagnetic sensing hardware with a smaller footprint, a small computing system, and encrypted data transmission over Wi-Fi, all contained within the device frame. We propose to test this system and the approach of at-home patient measurement in a cohort of 16 patients with diaphyseal tibia fractures. The ability of the dhDEC system to monitor the healing process and predict fracture healing outcomes will be evaluated and compared to standard radiographic evidence. Successful completion of this proposal will establish the feasibility of using a telemedicine approach to obtain measurements of fracture stability at frequent time intervals during the critical early healing time period. The proposed telemedicine system may provide a significant cost savings to the medical system while delivering a substantial improvement in fracture healing management, and, ultimately, patient outcomes.